The increasing demand of fuel leading to fuel shortages along with increased energy costs and environmental concerns have created a need for alternative energy sources, particularly those that are renewable. Biofuels have become a popular alternative fuel source because they are renewable.
As the demand for Biofuel and renewable industrial chemicals grows, so does the demand for Biomass. At very large scales of operation, the consolidation and transportation of large volumes of low density biomass overland is expensive and consumes a significant part of the energy generated. Biomass is grown on arable land, using large amounts of freshwater for irrigation and fertilizer. At a certain scale therefore, the demand for Biomass for Energy and industrial use begins to compete with Agriculture for the purpose of food production leading to unacceptable stresses in the food supply chain with a consequent escalation of food prices. In addition, the processing of Biomass to Biofuel and renewable chemicals at very large scales also involves the use of extremely large quantities of fresh water for hydrolysis the biomass as well as for fermentation. Given the increasing shortage of fresh water resources, this represents a scalability issue. Furthermore any such industrial process results in the formation of large quantities waste streams which need to be treated and disposed of in an environmentally acceptable manner. All of these issues could be prohibitive barriers in implementing such Biomass based processes widely and on a large scale.
Biomass produced from traditional agriculture or forestry operations has been the main source of fermentable sugars for the production of a variety of useful products including renewable industrial chemicals and Biofuel. The process of converting any kind of terrestrial biomass to such products generally involves collection and transportation of the biomass to a central processing location, pre-treatment of the biomass to make it amenable to further conversion, optionally followed by a treatment to break down the carbohydrate component of this biomass to fermentable sugars, followed by fermentation of these sugars with an appropriate strain of microorganism to produce the renewable industrial chemical or biofuel of interest.
Crops such as corn have been considered for producing biofuels because they are capable of being converted to alcohol. When ethanol is made from corn, it arguably takes more energy to produce the ethanol than is actually obtained from it. Also, using a grain such as corn for fuel precludes it from being used as food for humans. Corn production is also hard on the land because it erodes the soil. However, a biomass such as algae is capable of creating a fuel with a high power density, is renewable and, unlike corn, does not take away a food source from humans and livestock. The alternative to terrestrially grown Biomass is to use aquatic photosynthetic biomass such as seaweed that can be easily grown in the sea, without using freshwater and fertilizers.
The energy in biomass can be accessed by turning the raw materials, or feedstocks, into a usable form. Transportation fuels made from biomass through biochemical or thermochemical processes are known as biofuels which include ethanol, methanol, biodiesel, biocrude, and methane.
Ethanol is the most widely used biofuel today. Ethanol is an alcohol, and most is made using a process similar to brewing beer, in which starch crops are fermented into ethanol, which is then distilled into its final form. Ethanol made from cellulosic biomass materials instead of traditional feedstocks (starch crops) is called 2nd generation bio-ethanol. Ethanol can be used in its pure form (neat), as a blend with gasoline, or as a fuel for fuel cells. Ethanol is added to gasoline as an oxygenate to improve vehicle performance and reduce air pollution.
Methanol is also an alcohol that can be used as a transportation fuel. Currently produced using natural gas, methanol can be produced from biomass through a two-step thermochemical process. First the biomass is gasified to produce hydrogen and carbon monoxide. These gases are then reacted to produce methanol. Methanol can be used in its pure form, as a feedstock for the gasoline additive methyl tertiary butyl ether (MTBE), or as fuel for fuel cells.
Biodiesel is a renewable diesel fuel substitute that can be made by chemically combining any natural oil or fat with an alcohol (usually methanol). Many vegetable oils, animal fats, and recycled cooking greases can be transformed into biodiesel and there are many different ways to do it. Biodiesel can be used neat or as a diesel additive and is typically used as a fuel additive in 20% blends (B20) with petroleum diesel in compression ignition (diesel) engines. Other blend levels can be used depending on the cost of the fuel and the desired benefits.
Biocrude is a product similar to petroleum crude and can be produced from biomass using a fast pyrolysis process. Biocrude is formed when the biomass derived oil vapors are condensed. Catalytic cracking then converts biocrude into transportation fuels.
Methane is the major component of compressed natural gas, an alternative transportation fuel. Methane, in a blend of other gases, can be produced from biomass by a biochemical process called anaerobic digestion.
U.S. Pat. No. 6,893,479 describes a process to crush or homogenize the red seaweed to produce filterable slurry which can be separated to give the salt containing fluids and granules containing carrageenan. Removal of the sap is a means of efficiently producing dry seaweed granules and sap separately.
U.S. Pat. No. 7,479,167 describes a method for production of biofuels from the open ocean, wherein the method comprises testing the currents to determine that a seaweed biomass remains in a zone suitable for harvesting, harvesting a portion of the biomass and processing a portion of the harvested biomass to produce useful components of biofuels. The patent further describes a method for the producing an increased seaweed biomass to be proceeds into a biofuel from the surface of the ocean waters using the comprising the steps of testing a water surface of an ocean to determine a time period that the water will remain for a biomass generation, and testing the currents to determine that any biomass produced remains in a zone suitable for harvesting; testing the water surface to determine a first nutrient that is missing to a first extent that limits the growth of a first plant life; applying the first missing nutrient in a form that remains available to the first plant life; harvesting a first harvested portion of an increased biomass of the first plant life that results from the applying; and removing a first returnable portion from the first harvested portion to leave a remainder of the first harvested portion, and spreading the first returnable portion on the water surface.
U.S. Pat. No. 7,985,267 describes a method of producing biofuel from the surface of the ocean waters comprising the steps testing a water surface of an ocean to determine a time period that the water will remain for a biofuel generation; testing the water surface to determine a first nutrient that is missing to a first extent that limits the growth of a first plant life; applying the first missing nutrient in a form that remains available to the first plant life; harvesting a first harvested portion of an increased biomass of the first plant life that results from the applying; removing a first returnable portion from the first harvested portion to leave a remainder of the first harvested portion, and spreading the first returnable portion on the water surface; and processing the remainder of the first harvested portion into a biofuel component.
U.S. Pat. No. 7,479,167 and U.S. Pat. No. 7,985,267 specifically describe in order to increase seaweed biomass fertilization of the open ocean with a fertilizer system that comprises one or more fertilizers and suitable plant systems is necessary for production of biofuels from seaweed biomass.
WO2011/027360A1 (CSMCRI) describes a process for producing ethanol and seaweed sap from the red seaweed Kappaphycus alvalrezii, wherein the process comprises harvesting the kappaphycus seaweed, extracting the sap to leave carrageenan rich granules, then washing the granules to remove salt and silt before using acid to hydrolyse the carbohydrates to fermentable sugars followed by neutralization of the acid, removal of the salts by electrodialyis followed by fermentation using yeast. The process described in this patent application emphasizes the removal of salts principally because the salts are inhibitory to the fermentation by the yeast to ethanol.
WO2008/105618A1 (Korea institute of industrial technology) describes production of ethanol from red Seaweed Gelidium amansii. The seaweed was prepared first by washing dried seaweed with distilled water, followed by drying and pulverizing, before hydrolysis using acid or enzymatic means in aqueous solutions that do not contain any added salt.
WO2010/098585 describes a method for production of biofuels from seaweed extracts by hydrolysing the extract in a presence of a heterogeneous catalyst and converting the hydrolysate through enzymatic fermentation or chemical reaction into the biofuels. The process described in the application uses extract of the seaweed for producing biofuels. The seaweeds biomass as such has not been used in the process.
Goh and Lee (C. S. Goh, K. T. Lee; A visionary and conceptual macroalgae-based third generation bioethanol (TGB) biorefinery in Sabah, Malaysia as an underlay for renewable and sustainable development, Renewable and Sustainable Energy Reviews 14; 2010; 842-848) describes the hypothetical potential to produce ethanol and other by products from the seaweed Euchema spp. The authors describe a flow diagram for the process which suggested that the seaweed be first dried, and then powdered before being processed to various by-products, including ethanol. Goh and Lee further describe in detail as to how the seaweed may first be dried and subsequently the dried seaweed may be transported by boat and that the seaweed should be desalinated otherwise problems could be caused during purification.
Thus, the most of the processes for production of seaweed biomass known in the prior art describe removal of salt from the seaweed before further processing. Further, freshwater and/or fertilizer have been used in the cultivation of seaweeds and further processing of seaweed for producing useful chemicals and biofuel.
Furthermore, it is clear from the above that while the cultivation of seaweeds in the sea avoids the requirements for fertilizer and fresh water during cultivation, the above observations represent the commonly held views on how seaweeds may be collected and processed. Current scientific information suggests that the downstream process, starting with drying and transportation followed by hydrolysis and fermentation are carried out in a conventional manner, using freshwater that is not different from the way land based agricultural biomass is treated. Such processes at a large scale, using large amounts of fresh water and generating correspondingly large amounts of waste to be disposed off are not scalable and sustainable. Therefore, there is a need to provide a cost effective, an easy, sustainable, less time consuming process for production of biofules from seaweed biomass.
Any publications discussed above and throughout the text are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior disclosure.